1. Field of the Invention
The present invention relates to methods for forming a minute pattern and a semiconductor memory device using the same. In particular, the present invention relates to an improved method for forming a minute island-type pattern on a semiconductor substrate.
2. Description of the Related Art
In general, manufacturing of semiconductor devices may include a series of processes, e.g., a layer forming process, a photolithography process, an etching process, a planarization process, and so forth, to facilitate formation of patterns, e.g., an island-type pattern, on a semiconductor substrate.
A conventional island-type pattern on a semiconductor substrate may be formed as follows. First, a lower electrode layer may be deposited on a semiconductor substrate followed by sequential application of first and second mask layers thereon. A photoresist pattern may be formed in a center of an upper surface of the second mask layer. Next, the photoresist pattern may be used as an etch mask to remove peripheral portions of the second mask layer, thereby forming a pattern in the second mask layer. Similarly, the patterned second mask layer may be used as an etch mask to remove peripheral portions of the first mask layer, thereby forming a pattern in the first mask layer. The first and second patterned mask layers may have identical widths, thereby forming a uniform etch mask for etching an island-type pattern in the electrode layer. Alternatively, due to a relative large width of the island-type pattern formed in the electrode layer, only one mask layer may be used for etching.
If an island-type pattern is to be formed in an electrode layer of a highly integrated semiconductor, a relative low width, i.e., about 100 nm or less, would be desired, which would require formation of etch masks having similarly low widths. However, formation of a photoresist pattern with a width of about 100 nm or less may be difficult, e.g., due to limited resolution of the exposure equipment. Even if formation of a photoresist pattern having a width of about 100 nm or less is potentially attempted, the photoresist pattern may be easily separated during the etching process, thereby generating a non-uniform island type pattern on the semiconductor substrate.
Accordingly, there exists a need for an improved method of manufacturing a minute pattern with a relatively low width in a semiconductor device.